Valve



Sept. 19, 1967 B. A. ABERCROMBIE 3,342,203

VALVE Filed June 14, 1965 izzr l NVENTOR.

BY Mm f lc United States Patent 3,342,203 VALVE Bolling A. Abercrombie,Houston, Tex., assignor, by mesne assignments, to McMurry Oil ToolSpecialties,

Inc., Houston, Tex., a corporation of Texas Filed June 14, 1965, Scr.No. 463,550 r 12 Claims. (Cl. 137-155) ABSTRACT OF THE DISCLOSURE A gaslift valve apparatus having both a shutoff valve assembly and athrottling valve assembly, such throttling valve being connected toclose prior to closure of the shutoff valve assembly and to openfollowing the opening of the shutoff valve assembly.

This invention relates to a valve having a double seat. Moreparticularly, the present invention relates to a valve which isconstructed with a double seat, variable orifice, so that it will have along life occasioned by the elimination of throttling across the mainseat of the valve.

While the valves constructed in accordance with this invention areuseful in many systems, they find particular utility in the oil and gasindustry in the so-called gas-lift art.

In the gas-lift art, the gas may be a hydrocarbon gas, air or any othergas (though for safety reasons it is preferably one that will notsupport combustion in the context of its use). In all events, in thisspecification gas should be understood to mean gaseous type fluidsgenerally, and not just hydrocarbon ticular gas.

In the operation of oil wells, and especially in wells wherein thepressure in the formation is insufficient for the economical operationof the well by formation pres sure alone, it is customary to make use ofgas-lift mechanism by which gas under pressure may be introduced intothe well from the surface to promote the outflow of oil.

The gas-lift method of well operation is usually carried out byconnectinginto the well tubing a number of gaslift valves which areoperable to permit the inflow of gas under pressure from the interior ofa gas injection conduit, usually the annulus between well tubing andwell easing, into a production conduit, usually the tubing, atlongitudinally spaced intervals to cause an upfiow of oil and gas in thetubing. The gas-lift valves used in this method of operation areadjusted to be opened and closed upon the occurrence of approximatelypredetermined pressure conditions in the tubing and/ or casing, so thatgas is permitted to enter the tubing only at a location and underpressure conditions to cause an outflow of oil.

In the operation of wells by this method one gas-lift valve in a stringmay be opened continuously for long periods of open flow, or a valve maybe opened periodically to introduce gas under pressure from the annulusinto the tubing intermittently.

Oil may be aerated by the gas injected into the production tubing, andthereby lightened for easier flowing; this is commonly known as thecontinuous flow technique. On the other hand, slugs of gas in a singlebubble may be introduced into the well to act as a piston lifting a slugofoil, much as a bubble of steam in a coffee percolator lifts waterupward in the percolators tubing; this is the intermittent flowtechnique.

In one application of this general production method, gas-lift valvesare provided with mechanism by which the valves are held in closedposition by a predetermined force and are opened when the combination ofpressure in the well annulus and well tubing exceeds a predetermined gasor any other par- 3,342,203 Patented Sept. 19, 1967 pressure value. Suchvalves are often constructed with closed bellows which are filled withgas under pressure and positioned to exert a closing force on the valveand to be acted upon by the pressure in the annulus to open the valvewhen this combination of pressures reaches a predetermined value. Bythe-use of a suitable timing mechanism for controlling the flow of gasfrom the surface source of gas under pressure into the well annulus, theopening of valves of this type may be regulated to introduce gas fromthe annulus into the well tubing at predetermined clock-determinedintervals to cause the outflow of oil from the well through the tubing.

By the use of gas-lift valves of this type, the annulus pressure may bemaintained at a predetermined value so that when the level of liquid inthe tubing rises to a height to increase the pressure in the tubing onthe valve by a predetermined amount, the valve will open.

In this and other systems, one of he biggest problems in the prior artstructures is that the valves tend to throttle across the main valveseat. Such throttling, of course, results, in erosion of the valve stemand the adjacent valve seat. And the result of such erosion, of course,is that the useful life of the valve is greatly reduced, when comparedwith the projected life span of the same valve should such erosion beabsent.

Since valves may be located at remote places in a system, for example,down-hole in the oil or gas well, it is often greatly expensive andinconvenient to replace a worn-out valve. A shut-down of a process maybe necessary, but in any event, it is obvious that great savings intime, money, and efiiciency could result if a valve of longer life couldbe devised.

Accordingly, this invention seeks to provide an improved valve whicheliminates throttling across the main seat of the valve at closure. Theelimination of such throttling results in a valve which gives acceptableperformance over periods of time much longer than that for valvespresently on the market, due to the fact that the main seat of the valveconstructed in accordance with the present invention is not cut awaybythrottling gas. Valves constructed in accordance with this invention arethus efficient over relatively long periods of time, when compared withthe prior art structures.

In order that the manner in which the foregoing and other objectsattained in accordance with the invention can be understood in detail,one advantageous embodiment 'of the invention will be described withreference to the accompanying drawings, which form a part of thespecification, and wherein:

FIGURE 1 is a horizontal section view of a valve constructed inaccordance with one embodiment of this invention, showing the valve inthe closed position.

FIGURE 2 is a horizontal section of the valve of FIG- URE 1, wherein themain stem is in the open position and the throttling stem is in theclosed position.

FIGURE 3 is a horizontal view of the valve of the FIGURE 1 embodiment,showing the valve in the throttling position.

FIGURE 4 is a horizontal section view of the valve illustrated in FIGURE1, showing the valve in the full open position.

FIGURE 5 is an exploded section view of the throttling stem portion ofthe valve stem, illustrating in detail the scratches on the surface ofthis throttling stern portion.

The preferred embodiment of this invention, which is illustrated in theabove figures, may be characterized as a valve 2 which comprises anouter casing or housing 4. This outer casing or housing includes, at oneend thereof, a coupling element 6 which is in threaded engagement at 10with the remainder of the housing. Also included in the housing areapertures 48 which are upstream from the valve seat. These aperturesallow the pressure upstream of the valve seat to be the same as thepressure in the environment on the exterior of the housing. Forinstance, when the valve seat to be used in a gas-lift system, the valvestem will be exposed to the so-called casing pressure, while thepressure at the valve seat will be tubing pressure.

Coupling element 6 has a lower end counterbore 8 opening into theinterior of the upper housing section 4 and within which counterbore anannular valve seat forming member 12 is positioned. The seat formingelement may be retained in the counterbore by means of a snap ring 14releasably fitted into an internal groove 22 provided for the same inthe coupling element 6. Suitable seal forming means, such as the O-ring16 is disposed in a groove provided for the same in the seat formingelement to form a fluid tight seal between the seat forming element andthe coupling element 6.

Valve member 24 is comprised of a main stem 26 and a throtting stem 28,the throttling stern and the seat forming element 12 being soconstructed that the throttling stem will seat before the main stem ofthe valve.

Throttling stem 28 comprises a body portion 40 and a head portion 42.Body portion 40 is cylindrical in shape and extends axially into mainstem 26, being sealed in sliding engagement therein by quad ring 44.Head portion 42 of throttling stem 28 projects beyond the seat end ofthe main valve stem, so that this head portion must necessarily seatbefore the main stem will seat.

Although the head portion 42 of throttling stem 28 may take variousforms, the construction shown in the accompanying drawings is preferred;here the head portion is shown in the form of a frustro-conical section.Running along the surface of said section, between the small base andthe large base, and parallel to the altitude of the section, are one ormore scratches 30, which are shown particularly well in FIGURE 5.

Main stem 26 has therein apertures 34 which are in exact alignment onopposite sides of the main stem. Of considerably smaller diameter thanthese apertures is pin 36, which is engaged with the body portion ofthrottling stem 14 through said apertures. The throttling stem is thusfree to move back and forth along the axis of the main valve stem withinthe limits controlled by the relative sizes of the pin 36 and theapertures 34. That is, the throttling stem is free to slide back andforth relative to the main stem as long as the pin 36 is within theaperture portion of the main stem; but when the pin comes into contactwith the main stem itself, movement is of course stopped.

Main stem 26 has an externally threaded projection 38 at its endopposite the valve seat, at which point the main stem is in engagementwith the valve carrier 32. It is understood that the carrier 32 may beactuated by any conventional urging means (not shown) which will urgethe carrier to move the valve member to seat.

Reference may be made to McMurry Patent No. 3,175,- 514, issued Mar. 30,1965, for a more complete understanding of such an actuating mechanism.

Valve seat-forming element 12 comprises a main seat 18, and is taperedinwardly from said main seat to a throttling seat 20. The taperedinternal portion of the seatfor'ming' member will generally correspondto the construction of the head portion 42 of the throttling stem 28,

so as to mate with this head portion. Thus in the embodi- 6 mentillustrated, the hollow interior portion of the seatforming memberbetween the main seat 18 and the throttling seat 20 is in the form of afrustro-conical section.

As is more clearly seen in FIGURE 5, the head portion 42 of thethrottling stem and the tapered internal portion of the seat-formingmember do not exactly mate. That is, there is a constriction or seat 56at some point intermediate the ends of head portion 42 when the valve isin the FIGURE 1 position. And, of course, it is at point 56 that thevalve is closed when in that position.

It is seen that when the valve is open, i.e., when neither the main stem26 or the throttling stem 28 is seated, there is communication betweenthe fluid in the area 52, and the area 54, through the volumes 60 and 62and the port 50. On the other hand, when the valve is closed, there isno such communication.

The annular area at the end of main valve stem 26 which is exposed tothe volume 60 when the valve is in the position shown in FIGURE 1 isnoted as the area 58. This area corresponds, of course, to thedifference in the circumference defined by the seat 18 and thecircumference of the body portion 40 of throttling valve stem 28. Thearea of the top of head portion 42 of throttling valve 28 is noted asthe area 46.

Operation The operation of valves constructed in accordance with thisinvention can be best understood by reference to the illustratedembodiment and the accompanying drawings, FIGURES 1-4. In order to fullydescribe one particularly useful embodiment, the operation of the valvewill be described as used in a gas-lift system.

In FIGURE 1, the illustrated valve is shown in the closed position,i.e., there is no communication between the fluid in the area 52 and thearea 54 through the port 50. In normal operations in the gas-liftsystem, the area 52 represents the area occupied by the gas in theannulus between the tubing and the borehole; the pressure exerted bythis gas will be termed the casing pressure. The area 54 represents thearea occupied by the fluid inside the tubing of the well; the pressurein this area will be termed the tubing pressure.

When the relative pressures of the gas in the casing, the gas in thetubing, and the pressure exerted by the urging means become such (see,for example the afore mentioned patent to McMurry) that the valve tendsto open, it will do so in the order illustrated in FIGURES 2, 3, and 4.First, the valve will assume the position illustrated in FIGURE 2. Inthis position, the main stem 26 has moved away from the main seat 18allowing casing pressure to enter volume 60 to replace the tubingpressure which had occupied this volume 60 when the valve was in theFIGURE 1 position. Since the casing pressure must be greater than thetubing pressure, this change exerts an additional opening force on themain stem 26 equal to the pressure differential between casing andtubing pressure times the annular area 58 of the valve stem which isexposed to volume 60 when the valve is in the FIGURE 1 position. Thusthe main stem 26 is urged away from the main seat until the apertures 34come in contact with the pin 36. At this time, an additional forceurging the valve to remain closed is added to the system. Thisadditional force is equal to the pressure differential between thecasing pressure and the tubing pressure times the area of the endportion 46 of the head 42 of throttling stem 28. In the preferredembodiment of this invention, the annular area 58 is slightly greaterthan the area of the top 46 of head portion 42 of throttling stem 28, sothat when the main stem 26 opens, the valve immediately assumes theposition shown in FIGURE 2. In the FIG- URE 2 position, fluid passage isonly across the scratches 30 with tubing pressure being maintained inarea 54 and easing pressure being maintained in area 52 and volume 60.

Additional force urging the valve open, either an increase in tubingpressure or casing pressure, will cause the valve to assume the positionshown in FIGURE 3. The additional movement of the head portion 42 of thethrottling stem 28 allows an increased area 62 for fluid flow betweencasing and tubing. correspondingly a decrease in either casing pressureor tubing pressure will cause the valve member 24 to move toward theclosed position, thus decreasing the area 62 and further restricting thepassage of fluid between casing and tubing, or even a return to theFIGURE 2 position. Thus it can be seen that with the valve positioned asshown in FIGURE 3, exact control of fluid passage can be achieved andall tendency for erosion is located downstream of the main valve seat 18and stem 26.

Since the opening force exerted by the casing pressure is normally muchgreater than that exerted by the tubing pressure, it can be seen that bya small variation in casing pressure the flow passage and thus the flowvolume can be increased greatly without a considerable increase incasing pressure, as required where a fixed area choke or throttlingdevice is used.

Where the opening forceis increased considerably, thus urging the valvemember 24 to the position shown in FIGURE 4, the flow area 62 no longerremains the primary restriction to flow, this restriction beingtransferred to port 50. In this position, an additional force urging thevalve to remain open is added to the system, this force being equal tothe differential pressure between casing and tubing times the areadefined by seat 56. In the FIGURE 4 position, since port 50 is theprimary restriction, it can be seen that the entire force exerted tohold the valve open is exerted by the casing pressure, changing thecharacteristics of the system to such that a decrease in casing pressureis necessary for the valve to close. In other words, the system is nolonger responsive to tubing pressure. This is the type of operationnormally used for socalled intermitting lif whereas the throttling typeof operation is usually used for continuous flow. Thus it can be seenthat the system embodied by this invention can accomplish both types ofgas lift, i.e., continuous flow where the lift fluid is injectedcontinuously into the annulus between the tubing and casing; orintermittent lift where gas is injected intermittently at very rapidrates into the annulus, thus causing a rapid pressure increase therein.

A decrease in the casing pressure which urged the valve to assume theposition shown in FIGURE 4 will cause the valve member 24 to reassumethe position shown in FIGURE 3, thus allowing the flow restriction torevert to the throttling head 42 and the throttling seat 20, preventingthrottling across the main seat 18 and stem 26 and causing tubingpressure to again become an effective force urging the valve to remainopen. From the position shown in FIGURE 3, a further decreaase in eithercasing or tubing pressure will cause the valve to assume the positionshown in FIGURE 2 whereby the only flow passage is through the scratches30. In this position, casing pressure only urges the main stem 26 toremain in the open position, so only a decrease in casing pressure willcause the main stem 26 to move to the main seat 18. When the main stem26 moves toward the main seat 18 sufliciently to cause a restrictionsmaller than that of the scratches 30, the pressure in volume 60 changesfrom casing pressure to tubing pressure, thus removing a portion of theforce urging the main stem 26 open and causing the main stem to snapclosed. This snap action prevents any possibility of throttling acrossthe main stem 26 and main seat 18.

It is thus seen that a distinctly advantageous valve has been developedwhich will solve the aforementioned problems with simplicity andefficiency. Though the valve of this invention has been described interms of one embodiment which has been found to be particularlyadvantageous, it is apparent that numerous changes might 'be made in thevalve or in the system in which it is used without departing from thescope of this invention.

What is claimed is:

1. A combination throttling and shutoff valve assembly comprising ahollow valve body having a first inlet and a second inlet and having afluid passageway therebetween encompassed by a shutoff seat at a firstlocation and a throttling seat at a second location spaced between saidfirst location and said second inlet,

a throttling member disposed in said passageway to be 6 urgedagainstsaid throttling seat for throttling fluid flow through saidpassageway, and

a shutoff member trailingly disposed in said passageway relative to saidthrottling member to be urged into fluid-tight engagement with saidshutoff seat following engagement of said throttling member'with saidthrottling seat.

2. The valve assembly as described in claim 1, wherein said throttlingmember is urged against said throttling seat in response to a pressuredifferential across said throttling and shutoff seats.

3. The valve assembly as described in claim 2, wherein said throttlingmember is movable into throttling engagement with said throttling seatindependently of said shutoff member.

4. The valve assembly as described in claim 3, wherein said shutoffmember is slidably disposed about said throttling member for disengagingfrom said shutoff seat and after moving independently of said throttlingmember a limited distance from said shutoff seat engaging with andmoving said throttling member out of throttling engagement with saidthrottling seat.

5. The valve assembly as described in claim 4, wherein said shutoffmember and said throttling member are cooperatively movable toward saidthrottling seat until said throttling member engages said throttlingseat, and

wherein said shutoff member is thereafter movable into engagement withsaid shutoff seat independently of said throttling member.

6. The valve assembly as described in claim 5, wherein said shutoff seatencompasses a larger cross sectional area than said throttling seat.

7. The valve assembly as described in claim 6, wherein said throttlingmember is provided with at least one groove to permit a limited fluidflow across said throttling seat when in throttling engagementtherewith.

8. The valve assembly as described in claim 6, wherein said assemblyincludes a hollow valve insert removably disposed in said valve bodyacross said passageway, and

wherein said shutoff and throttling seats are located in said valveinsert.

9. A combination throttling and shutoff valve assembly comprising ahollow valve body having a first inlet for communication with a firstpressure and a second inlet for communication with a second pressure andhaving a fluid passageway therebetween with a shutoff seat portionencompassing said passageway at a first location and a throttling seatportion encompassing said passageway at a second location spaced betweensaid first location and said second inlet,

a throttling member disposed between said throttling seat and said firstinlet to be moved by said first pressure into throttling engagement withsaid throttling seat in response to a differential between said firstand second pressures, and

a shutoff member for sealing engagement with said shutoff seat andfurther adapted. after disengaging and moving a limited distance fromsaid shutoff seat to engage and move said throttling member out ofthrottling engagement with said throttling seat.

10. A combination throttling and shutoff valve assembly comprising ahollow valve body having a high pressure inlet and a low pressure inletwith a passageway therebetween and having a shutoff seat encompassing afirst area and a throttling seat spaced from said shutoff seat generallytowards said low pressure inlet and encompassing a second area smallerthan said first area,

a throttling valve member movably disposed in said valve body betweensaid throttling seat and said high pressure inlet and having athrottling head adapted to be urged into throttling engagement with saidthrottling seat by fluid pressure through said high pressure inlet and ashank member extending through said shutoff seat generally towards saidhigh pressure inlet, 4 I

a shutoff valve member movable to and from said shutofl? seat inresponse to variations in fluid pressure adjacent said high pressureinlet and having a shutoif head slidably disposed about said shankmember and adapted for fluid-tight engagement with said shutofl seat,and

linking member connected with said shank member for engagement with saidshutoff valve member to draw said throttling head out of throttlingengagement with said throttling seat after said shutofi valve membermoves out of engagement with and away from said shutoff seat apreselected distance.

11. The valve assemblydesc-ribed in claim 10, including sealing meansdisposed about said shank member to provide a fluid seal between saidshank member and said shutofi head.

References Cited UNITED STATES PATENTS Knauf 137-629 Rose 137630.14Hurlbu'rt 137-63014 Lilly 103232 McMurry 103232 Garrett 137155 Carializo2 103232 DONLEY J. STOCKING, Primary Examiner.

W. I. KRAUSS, Assistant Examiner.

1. A COMBINATION THROTTLING AND SHUTOFF VALVE ASSEMBLY COMPRISING AHOLLOW VALVE BODY HAVING A FIRST INLET AND A SECOND INLET AND HAVING AFLUID PASSAGEWAY THEREBETWEEN ENCOMPASSED BY A SHUTOFF SEAT AT A FIRSTLOCATION AND A THROTTLING SEAT AT A SECOND LOCATION SPACED BETWEEN SAIDFIRST LOCATION AND SAID SECOND INLET, A THROTTLING MEMBER DISPOSED INSAID PASSAGEWAY TO BE URGED AGAINST SAID THROTTLING SEAT FOR THROTTLINGFLUID FLOW THROUGH SAID PASSAGEWAY, AND A SHUTOFF MEMBER TRAILINGLYDISPOSED IN SAID PASSAGEWAY RELATIVE TO SAID THROTTLING MEMBER TO BEURGED INTO FLUID-TIGHT ENGAGEMENT WITH SAID SHUTOFF SEAT FOLLOWINGENGAGEMENT OF SAID THROTTLING MEMBER WITH SAID THROTTLING SEAT.